package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisData;
import io.netty.util.internal.StringUtil;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;

import java.time.LocalDateTime;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {
    @Resource
    private StringRedisTemplate stringRedisTemplate;;
    @Autowired
    private CacheClient cacheClient;

    @Override
    public Result queryById(Long id) {
        //缓存穿透
//        Shop shop = cacheClient
//                .queryWithPassThrough(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);

//        //互斥锁解决缓存击穿
//        Shop shop = queryWithMutex(id);
        //逻辑过期缓存击穿
        Shop shop = cacheClient
                .queryWithLogicalExpire(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);
        if (shop == null) {
            return Result.fail("店铺不存在");
        }
        return Result.ok(shop);
    }

    //线程池
//    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);

    /*
    public Shop queryWithLogicalExpire(Long id){
        String key = CACHE_SHOP_KEY + id;
        //1.从redis中查询店铺信息
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if (StrUtil.isBlank(shopJson)) {
            //3.存在，直接返回
            return null;
        }
        //4.命中，先把json反序列化为对象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        Shop shop = JSONUtil.toBean((JSONObject) redisData.getData(), Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();
        //5.判断是否过期
        if (expireTime.isAfter(LocalDateTime.now())) {
            //5.1未过期,直接返回
            return shop;
        }
        //5.2已过期，缓存重建
        //6.重建缓存
        String lockKey = LOCK_SHOP_KEY + id;
        //6.1 获取互斥锁
        boolean isLock = tryLock(lockKey);
        //6.2判断是否获取成功
        if(isLock){
            //6.3成功,开启独立线程,实现缓存重建
            CACHE_REBUILD_EXECUTOR.submit(() -> {
                try {
                    //重建缓存
                    this.saveShop2Redis(id, 20L);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }finally {
                //释放锁
                unLock(lockKey);
                }
            });
        }
        //6.3 成功,开启独立线程,实现缓存重建
        //6.4返回过期的店铺信息
        return null;
    }
     */
    /*
    public Shop queryWithMutex(Long id){
        String key = CACHE_SHOP_KEY + id;
        //1.从redis中查询店铺信息
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if (StrUtil.isNotBlank(shopJson)) {
            //3.存在，直接返回
            return JSONUtil.toBean(shopJson, Shop.class);
        }
        //2.1判断空值
        if (shopJson != null) {
            return null;
        }

        //4.实现缓存重建
        //4.1获取互斥锁
        String lockKey = LOCK_SHOP_KEY + id;
        Shop shop = null;
        try {
            boolean isLock = tryLock(lockKey);
            //4.2判断是否获取成功
            //4.3失败，休眠并重试
            if (!isLock) {
                Thread.sleep(50);
                return queryWithMutex(id);
            }


            //4.成功，根据id查询数据库
            Thread.sleep(200);
            shop = getById(id);
            //5.数据库不存在，返回错误
            if (shop == null) {
                //将空值写入redis
                stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL,TimeUnit.MINUTES);
                return null;
            }
            //6.存在，写入redis
            stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }finally {
        //释放互斥锁
        unLock(lockKey);
        }
        //7.返回
        return shop;
    }
*/
//    private boolean tryLock(String key) {
//        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
//        return BooleanUtil.isTrue(flag);
//    }
//
//    private void unLock(String key) {
//        stringRedisTemplate.delete(key);
//    }
//
//    public void saveShop2Redis(Long id,Long expireSeconds) throws InterruptedException {
//        //1.查询店铺数据
//        Shop shop = getById(id);
//        Thread.sleep(200);
//        //2.封装逻辑过期时间
//        RedisData redisData = new RedisData();
//        redisData.setData(shop);
//        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
//        //3.写入redis
//        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id, JSONUtil.toJsonStr(redisData));
//    }
//    @Override
    @Transactional
    public Result update(Shop shop) {
        Long id = shop.getId();
        if (id == null) {
            return Result.fail("店铺id不能为空");
        }
        //1.更新数据库
        updateById(shop);
        //2.删除redis
        stringRedisTemplate.delete(CACHE_SHOP_KEY + shop.getId());
        return Result.ok();
    }
}
